package com.felix.book.thinking.in.java;

/**
 * Callbacks
 *
 * @author xuejinhua
 * @date 2018/11/14 9:56
 */
// Callbacks.java
// using inner classes for callbacks

interface Incrementable{
    void increment();
}

// Very simple to just implement the interface:
class Callee1 implements Incrementable{
    private int i = 0;
    @Override
    public void increment(){
        System.out.println(++i);
    }
}

class MyIncrement{
    public void increment(){ System.out.println("Other operation"); }
    static void f(MyIncrement mi) { mi.increment(); }
}

// If your class must implement increment() in some other way, you must use an inner class:
class Callee2 extends MyIncrement{
    private int i = 0;
    @Override
    public void increment(){
        super.increment();
        System.out.println(++i);
    }
    private class Closure implements Incrementable{
        @Override
        public void increment(){
            // Specify outer-class method, otherwise you'd get an infinite recursion:
            Callee2.this.increment();
        }
    }
    Incrementable getCallbackReference(){
        return new Closure();
    }
}

class Caller{
    private Incrementable callbackReference;
    Caller(Incrementable cbh){ callbackReference = cbh; }
    void go(){ callbackReference.increment(); }
}

public class Callbacks {
    public static void main(String[] args){
        Callee1 c1 = new Callee1();
        Callee2 c2 = new Callee2();
        MyIncrement.f(c2);
        Caller caller1 = new Caller(c1);
        Caller caller2 = new Caller(c2.getCallbackReference());
        caller1.go();
        caller1.go();
        caller2.go();
        caller2.go();
    }
}